2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 75Get this manual
MAINTENANCE Remove the dust cover and clean it with compressed air if it is dirtyInstall the dust cover in position
DUST COVER Wash the element and filter in non-flammable or high flash point solventSqueeze out the solvent thoroughly, and allow the element and filter to dry
Wash Apply approximately 20 (0.7 oz) of Pro Honda Foam Filter Oil or equivalent oil from the inside of the elementPlace the element into plastic bag and spread the oil evenly by hand